Dunno. Would be cool to get a whole main harness and trace them. But it's just also like the plugs that are behind my headlights that are taped up too, and there are more under / behind the dash as well. I find it easier to ignore them instead of trying to figure them out as everything works.

I've come across it before, If its the one I'm thinking of, its actually a earth joiner for some of your sensors. There is a plug that appears to have a cap on it, the cap is a joiner, that joins the wires together. I've had a look at a wiring diagram as I've come across it when I did my engine conversion. In mine it joined the earth of the engine temp sensor, front 02 sensor, rear 02 sensor and Air flow sensor. The wiring diagram calls it "shield and sensor ground joint connector"